Concurrent Alcohol–Cannabis Use Did Not Necessarily Mean Same-Occasion Use

Using alcohol and cannabis within a general reporting period is different from using both during the same occasion. A review that included both definitions explicitly warned readers about the distinction before summarizing co-use findings.

The exposure definitions were not identical

Yurasek and colleagues distinguished concurrent use, meaning general use of both substances, from simultaneous use during the same occasion. Their review included studies using both definitions.

The combined co-use label therefore did not always identify the same behavior. A person counted as a concurrent user might not have taken the drugs close enough together for an acute interaction during a particular event.

The definition changes the research question

General co-use can help examine patterns of substance use, comorbidity and treatment. Same-occasion exposure is more directly relevant to an acute combined pharmacological effect.

A prevalence estimate or association from one definition cannot be transferred unchanged to the other. Nor does reporting both substances establish their timing in an individual case.

Read the time frame before interpreting the finding

The review noted that simultaneous-use studies were relatively limited in the literature it examined. That historical limitation is part of the synthesis, rather than a claim about all research available today.

The useful step is to identify the questionnaire period, occasion definition and outcome. These details prevent a broad behavior category from being mistaken for evidence of simultaneous intoxication.

Related: Interpreting cannabis tolerance claims.

Research cited

Yurasek AM; Aston ER; Metrik J Current addiction reports · 2017 · 4(2):184 PMID 32670740 · DOI 10.1007/s40429-017-0149-8. Co-use of Alcohol and Cannabis: A Review..